Topic Last Updated—August 2008

Multicast is an operating system deployment feature in Microsoft System Center Configuration Manager 2007 R2 that conserves network bandwidth by simultaneously sending data to multiple clients rather than sending a copy of the data to each client over a separate connection. Multicast allows multiple computers to download an operating system image package as it is multicast by the distribution point rather than each client being sent the package separately. This can conserve network bandwidth in environments where multiple clients are likely to be downloading the same operating system image at the same time. Clients can join a multicast session already in progress. When the multicast is complete, the client will then download missing portions of the package.

The information in this topic applies only to Configuration Manager 2007 R2 and Configuration Manager 2007 R3.

Multicast Prerequisites

Multicast for operating system deployment requires Microsoft System Center Configuration Manager 2007 SP1 and Microsoft System Center Configuration Manager 2007 R2 be installed and the Windows Deployment Services (WDS) extension be installed on Windows Server 2008 site system servers. For a full list of prerequisites for multicast, see Prerequisites for Multicast for Operating System Deployment.

Enabling and Configuring Multicast

To deploy operating system images by using multicast, the multicast feature must be enabled on the specific Configuration Manager 2007 distribution point. Branch distribution points cannot use multicast. For information about how to enable multicast, see How to Enable Multicast for Operating System Deployment.

After enabling multicast, configure multicast for the network environment. For more information about configuring for multicast, see About Configurations for Multicast for Operating System Deployment.

Scheduling Multicast

Administrators can further conserve bandwidth by specifying scheduling conditions to group multiple clients together. This consolidates client requests and optimizes the benefits of multicast but might require clients to wait until certain conditions are met to begin downloading the operating system image. The scheduling conditions can be configured to require a certain number of clients or a certain number of minutes before the multicast session begins. For more information about scheduling conditions for multicast sessions, see ConfigMgr Distribution Point Properties: Multicast Tab.

See Also